A medical examiner who reviewed video and photographs of George Zimmerman's injuries suffered during his fatal confrontation with Trayvon Martin called the neighborhood watch captain's wounds "insignificant" and "non-life threatening."

Dr. Valerie Rao testified that Zimmerman was struck as few as three times by Martin during the fight that night. She also asserted his head may have only been slammed on the concrete a single time. Zimmerman, who faces second-degree murder charges for the death of the unarmed teenager, said Martin repeatedly slammed his head on the concrete.

"Are the injuries on the back of the defendant's head consistent with one strike against a concrete surface?" asked prosecutor John Guy

"Yes," Rao said.

"And why do you say that?" asked Guy

"Because if you hit the head one time, it is consistent with having gotten those two injuries at that one time," she testified.

Rao's testimony could contradict Zimmerman's assertion that he was involved in a potentially life-threatening struggle with the Florida teenager.

Zimmerman, 29, claims he shot Martrin, 17, in self defense on Feb. 26, 2012 as Martin repeatedly banged his head against the pavement and reached for Zimmerman's gun.

"If you look at the injuries they are so minor they are not consistent with grave force," Rao said. "If somebody's head is banged with grave force I would expect a lot of injuries. I don't see that."

During the defense's cross examination of Rao, Zimmerman attorney Mark O'Mara got Rao to concede that his client's injuries could have been caused by more than three impacts. She also indicated that abrasions on Martin's knuckles were consistent with him striking someone.

The medical examiner's testimony came during a day in which prosecutors attempted to point out several inconsistent statements made by Zimmerman to others outside law enforcement.

Mark Osterman, who described Zimmerman as "the best friend he's ever had," testified that Zimmerman told him that Martin grabbed the gun in his holster before he shot him. But in an interview with FOX's Sean Hannity played in court today Zimmerman said he felt Martin's hands go towards the holster.

Martin's DNA was not found on the gun, and in several interviews with law enforcement Zimmerman said Martin reached for the gun, but never got it.

In the Hannity interview Zimmerman said that Martin "was like skipping, and going away quickly" not "out of fear." However, Zimmerman told a police dispatcher that the teen was running on the night of the shooting.

This testimony came after prosecutors asked the judge to strike a comment made by their own witness who told the court that Zimmerman was being truthful when he described his fatal fight with teenager Trayvon Martin.

The testimony by investigator Chris Serino on Monday seemed to bolster the credibility of Zimmerman's claim that he shot Martin in self defense because the teenager was banging his head into the sidewalk.

In commenting on the consistency of Zimmerman's story as well as Zimmerman's apparent relief when falsely told there was a video of the confrontation, Serino said Zimmemran had to be either a pathological liar or telling the truth.

"If we were to take pathological liar off the table…do you think he was telling the truth?" asked defense attorney Mark O'Mara.